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Posts: 1901
Location: MN | Does there seem to be a consensus on when or how often to change out the impeller on your outboard? Does size or age make a difference? I've been trying to put a new one in every third year - is this overkill? I have occasionally seen where it got a little dry but normally it seems to be in great shape whenever I've pulled them out. Mine is a '95 Merc 2 stroke. |
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Posts: 859
Location: MN | How many hours are you putting on the motor each year? |
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Posts: 349
| 300 hours or 3 years is typical. More often if you put sediment through it every so often. |
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Posts: 1901
Location: MN | NathanH - 4/23/2018 1:05 PM
How many hours are you putting on the motor each year?
Seems like a lot. 4 trips to LOTW each year, and we do lots of running there. Basically every weekend from mid-May through late Oct, plus a few longer trips in between. So let's say 60-80 days per year. But I don't think all of that adds up to even close to 300 hours a year of actual running time does it? |
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Posts: 349
| tswoboda - 4/23/2018 1:51 PM
300 hours or 3 years is typical. More often if you put sediment through it every so often.
Sorry, I just realized my post is confusing... I was referring to the impeller replacement interval. Replace every 300 hours or 3 years, whichever comes first. I think that's definitely on the conservative side, but that's what I remember seeing in a service manual.
Hours on a motor definitely differ by how it's used. I might put 14 hours on in a day of trolling but only travel 60 miles. Conversely, in a day on LOTW I might travel 75 miles but only put on 3 hours. |
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Posts: 1901
Location: MN | Maybe some of the guides that are putting in 200 +/- days a year can chime in - are you getting the impeller changed every year? Every other? I'm guessing their usage/hours would be nearly three times mine. |
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Posts: 386
| I think once every 3 years is a safe bet for most guys. |
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Posts: 1767
Location: Lake Country, Wisconsin | I’ve been told by mechanics over the years that every other year is the best way to go. I’d rather be safe than sorry |
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Posts: 770
| every other year. Regardless of use. |
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Posts: 3497
Location: Elk River, Minnesota | Hiya,
Impellers do see quite a bit of spinning, but to replace every other year in my humble opinion is a tad overkill. Safe?....yes.... But...the rubber is inside of a housing so UV rays will not affect it, dry rot is extremely minimal, and being that when the motor is properly run, there is water lubricating the impeller within the housing.
Unless you are out day in and day out with the motor running consistently such as trolling, I see no reason to replace for 3 years. I would say for the average fisherman (tongue firmly in cheek here) that most of us who cast probably put 50 hours on the main motor in a year...the trolling crowd obviously would be more..
If you have a water pressure gauge installed, the telltale would be when you see a drop in water pressure as compared to previous use/previous year. If the pressure is staying within a PSI or so from the previous year, you'd be safe.
Steve |
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Posts: 1901
Location: MN | Ah, pressure gauge. Good idea. Thanks Steve |
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Posts: 253
Location: Birchwood, WI. | I've always done the 3 year plan..What i have been told buy many to be the best plan anyway's... + Piece of mind...Better to be safe then sorry... |
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Location: Contrarian Island | every year is a bit overkill imo... every few for most of us is plenty.... some guys go about every 10 yrs  |
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Posts: 3497
Location: Elk River, Minnesota | Brad...your motor isn't THAT old yet!!
I agree with you, though... My father's 1973 Johnson 20hp didn't get a new impeller for almost 35 years. It was still working well and was in great shape when I changed it out...
Steve |
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Posts: 897
| Where you use it plays a role in how often you should change it in my opinion. Running around on Lake of the Woods or other bigger bodies of water where you might be 20 miles from the dock dictates more preventative maintenance.
Edited by whynot 4/25/2018 8:20 AM
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Posts: 3497
Location: Elk River, Minnesota | And here I was thinking you were going to mention the type of water you are running in....such as water that is very silty or mud suspended (like our beautiful Mighty Mississippi as it travels further south). Then I could see a shorter term maintenance schedule...
Heck... I should do mine on the rig I am currently in. 7 year old motor with only 98 hours on it, but it has a 300 hour service schedule. I'm going to see where pressure is now and determine next step from there. New boat to me so I don't even have a baseline yet.
Steve |
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Posts: 897
| VMS - 4/25/2018 12:31 PM
And here I was thinking you were going to mention the type of water you are running in....such as water that is very silty or mud suspended (like our beautiful Mighty Mississippi as it travels further south). Then I could see a shorter term maintenance schedule...
Steve
This, too. My point re: bigger bodies of water is the consequences of neglecting preventative maintenance are far greater when you're stuck out a long ways from home. |
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Posts: 3497
Location: Elk River, Minnesota | No doubt...
Although an impeller failure is not something that will be a single point catastrophic failure... It would show signs of wear such as a weak stream while under power or possibly no stream while idle...
In my humble opinion, something such as the size of the body of water one mainly runs on would still not require an impeller change every other year. They don't break down anywhere near that fast unless the motor is being consistently started out of the water creating a huge amount of friction in the housing along with heat... That just doesn't happen when water is present in the system.
Steve
Edited by VMS 4/25/2018 8:20 PM
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Posts: 1901
Location: MN | Steve, mine is a '95 Merc 2stroke. I've been told by a shop that the pee stream on these is not a very powerful one, especially at idle. Mine seems to be exactly that but works and never a problem. Does that sound right for this motor or wouldn't you know? |
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Posts: 3497
Location: Elk River, Minnesota | Hiya,
Honestly, I would not know. If there is a stream coming out, you have pressure of some sort....the only real way to tell is through a water pressure gauge to know really what is going on. I know my former 1999 Johnson 50hp was like a faucet coming out by design, by my recently sold 90 hp it was a small stream. Not extremely strong, but there nonetheless. With a pressure gauge, the 90 was pushing around 20 psi at full throttle, and below 10 at idle.
For those interested, a pressure gauge is not too hard of an install. It usually comes with all of the fittings for the install, but you would have to locate the outlet hole on the engine to install the fitting....install with a little thread tape, drill the correct hole in the instrument panel/location of choice, and you are good to go. It's not a necessary item unless you are running a hydraulic jackplate where you could easily drop your water pressure, but it is an extra gauge to monitor how the engine is doing.
When you think about it, it doesn't take a huge amount of pressure to move water around through the engine. Water is a pretty easy fluid to move with very little effort. That is why so many people out there have not replaced their impellers with any sort of regularity because if it's exiting the motor, all seems to be good. But...then again, many boats out there don't see the kind of use that harder-core fishermen can put their rigs through.
Steve
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Posts: 1741
Location: Mt. Zion, IL | new Evinrude Etec engines have a chart for rpm, hp, and pressure. I agree a gauge is the best way, but every manufacturer will most likely have different pressure requirements. |
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Posts: 323
Location: Elk River, MN | Propster - 4/25/2018 10:19 PM
Steve, mine is a '95 Merc 2stroke. I've been told by a shop that the pee stream on these is not a very powerful one, especially at idle. Mine seems to be exactly that but works and never a problem. Does that sound right for this motor or wouldn't you know?
I ran a 93 Merc 2 stroke for a while and it was the exact same. Nothing you'd be impressed with.
I always turn around a check for a stream when I fire up the motor. Had a few times after being shallow that i needed to stick a small wire into the output to knock loose some sediment. |
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Posts: 8806
| I've had to clean out the pee-hole. Is that a potential sign of low pressure (i.e. failing impeller) or do they just clog up sometimes? |
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Posts: 1901
Location: MN | Espy - 4/26/2018 1:08 PM
Propster - 4/25/2018 10:19 PM
Steve, mine is a '95 Merc 2stroke. I've been told by a shop that the pee stream on these is not a very powerful one, especially at idle. Mine seems to be exactly that but works and never a problem. Does that sound right for this motor or wouldn't you know?
I ran a 93 Merc 2 stroke for a while and it was the exact same. Nothing you'd be impressed with.
I always turn around a check for a stream when I fire up the motor. Had a few times after being shallow that i needed to stick a small wire into the output to knock loose some sediment.
That's good to know. And yes, even with regular cleaning out the hole, and with brand new impeller, always the same. Less than torrential. But seems to do the job. |
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Posts: 8806
| Propster - 4/26/2018 3:45 PM
Espy - 4/26/2018 1:08 PM
Propster - 4/25/2018 10:19 PM
Steve, mine is a '95 Merc 2stroke. I've been told by a shop that the pee stream on these is not a very powerful one, especially at idle. Mine seems to be exactly that but works and never a problem. Does that sound right for this motor or wouldn't you know?
I ran a 93 Merc 2 stroke for a while and it was the exact same. Nothing you'd be impressed with.
I always turn around a check for a stream when I fire up the motor. Had a few times after being shallow that i needed to stick a small wire into the output to knock loose some sediment.
That's good to know. And yes, even with regular cleaning out the hole, and with brand new impeller, always the same. Less than torrential. But seems to do the job.
If you can out pee your pee hole, you may have a problem with your impeller. |
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Posts: 3497
Location: Elk River, Minnesota | Hiya,
Depending on whether or not you have had a little silt, sand that has gotten in from, say, an inadvertant run in with a sand bar where some sand got sucked into the intake, the exit hole can sometimes get a little clogged here and there. the little paper clip trick to quickly clean it out is a good thing to do here and there as the exit is usually a restricted location of the water from a tube of some sort.
If you clean it out and it is just sputtering...not really a stream of any sort, then that is a sign it might be time to change out, or at least give it a look-see...
Steve |
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Posts: 8806
| Well, if I'm going to bother taking it apart to look at it, I may as well change it out. |
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Posts: 3497
Location: Elk River, Minnesota | Agreed...
Steve |
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